1. Technical Field
The present invention relates generally to cargo carrying vehicles. More particularly, the present invention relates to such vehicles having an on-board loading and unloading mechanism for loading containers onto the vehicle and unloading the containers therefrom. Specifically, the present invention relates to rear loading vehicles in which the containers are unloaded in a rearward direction.
2. Background Information
Within the vast field of cargo transportation, there are a host of vehicles and loading mechanisms for loading and unloading cargo from various vehicles. It is well known to use forklifts or other vehicles which are separate from the transportation vehicle which carries a container or other cargo from place to place. However, the use of such separate vehicles or loading mechanisms which are separate from the cargo carrying vehicle typically requires that a forklift or other such loading mechanism is available at the delivery location of the container or cargo. Thus, there is a substantial advantage of having a loading mechanism which is mounted on the cargo carrying vehicle so that the cargo may be unloaded at any delivery location regardless of whether there is a separate loading and unloading mechanism at the delivery site.
A variety of vehicles having onboard loading and unloading mechanisms are known in the art including side loading vehicles in which the cargo is moved from the vehicle to an unloading location to the side of the vehicle, as well as rear loading vehicles in which the cargo is removed to the rear of the vehicle. One of the drawbacks of side loading vehicles is the need for space to the side of the vehicle for unloading the cargo. In many instances, such space is simply unavailable. In other circumstances, it is problematic to unload cargo to the side of the vehicle, for instance when the vehicle must be parked on a roadway in order to load or unload the cargo and thus may be parked in a traffic lane and thus obstruct the flow of traffic. Another problematic area for side loaders is associated with a single width driveway whereby the cargo carrying vehicle would either be parked on the driveway and be required to unload the cargo onto the ground beside the driveway, or be parked on the ground beside the driveway to unload the cargo onto the driveway. Either scenario may cause problems especially where the ground is not very firm or is at an unsuitable angle for loading and unloading.
Roll-off systems fall within the rear loading category. These vehicles typically utilize a container which has wheels along the bottom of each side so that the wheels allow the container to roll off of a support platform of the vehicle. More particularly, the support platform is pivoted relative to the frame of the vehicle in order to facilitate the container rolling off of the platform onto the ground. One of the drawbacks of roll-off systems is the need for the vehicle to move forward during the unloading operation. More particularly, the platform is tilted so that the container rolls rearwardly until its rear end contacts the ground, at which time the vehicle is moved forward in order to allow the front end of the container to be lowered as it rolls off the platform until the container is fully unloaded. The need for the vehicle to move forward during this process requires additional space in order to unload the container. In addition, these containers are typically formed with sides that angle inwardly at the bottom to accommodate the wheels thereon, thus reducing the amount of cargo carrying space within the container.
Another rear loading apparatus which is commercially in use is described in U.S. Pat. No. 6,071,062 granted to Warhurst et al. and U.S. Pat. No. 6,155,770 granted to Warhurst. These two patents disclose a vehicle which carries a removable carriage and lift mechanism which itself lifts a container off of the vehicle and is independently operated to carry the container away from the vehicle. While this configuration allows the carriage to travel with the cargo carrying vehicle, the carriage must be completely removed from the vehicle in order to unload the container from the vehicle. The carriage thus requires a separate set of wheels and a motor for driving its movement on the wheels while carrying the container. During the unloading process, the carriage is also expanded axially or side to side so that it becomes wider than the cargo carrying vehicle in order to provide clearance to move rearwardly relative to the vehicle. The carriage thus requires additional side to side space during operation.
More recent rear loading vehicles are described in U.S. Pat. No. 7,074,004 granted to Lockamy et al. The Lockamy patent describes two embodiments for loading and unloading a container from a vehicle with an onboard loading and unloading mechanism. In one embodiment, a powered lift mechanism is positioned on the vehicle forward of the container which is loaded thereon. A pair of L-shaped arms is pivotally mounted on the lift mechanism with one leg of the L-shape extending downwardly from the pivot and the second leg of the L-shape extending rearwardly from adjacent the front of the container to adjacent the rear of the container. When the vehicle is traveling, these arms are pivoted inwardly toward one another, and are pivoted outwardly during the unloading operation. Flexible suspension members such as chains are hung from the pivot arms for supporting the container during the loading and unloading operation. With the container secured to the pivot arms via the chains or the like, the lift mechanism lifts the container and then moves rearwardly along a track so that the container is positioned rearwardly of the vehicle and then lowered. The other embodiment basically utilizes a carriage on which a pair of longitudinal beams of the carriage is telescopically mounted on a respective pair of longitudinal beams of the vehicle so that the carriage is movable rearwardly relative to the vehicle in order to move the container rearwardly therewith. A pair of wheels is mounted adjacent the rear of the carriage in order to support the carriage as it moves rearwardly. A lift mechanism on the carriage is also provided for raising and lowering the container via chains or the like from which the container is suspended.
While these various systems serve their purpose, there is a need in the art for a simple and cost effective rear loading vehicle which is simple to operate and which falls within a weight class which may be driven by an operator holding a driver's license for a passenger vehicle.